Hi Jules The formats for MFM and FM are mostly well defined but they are not the only formats out there. There was a problem with one of the early controller chips ( I think it was the 1791 ) that had problems with all 0 gaps or something. In general, FM is FM and MFM is MFM. The clock rates are different for 8 inch and 5-1/4, single, double and quad. There are at least two other common soft sectored formats that I know of. There is the Aplle II format and there is M2FM that Intel used. Hard sectored formats used all kinds of encoding. Most use a simple return to zero type clocking. Sector headers had any number of different combinations. Anyway, going directly into the port is always going to be tough for a PC. PC's are busy with a number of things and don't make particularly good "real time" processors. I'd been thinking of the same things you've been thinking of. There is another way. A while back there was some modem boards called "softmodems". These were made by Cardinal and DSI ( later bought by that sound board company? ). These have DSP chips that run quite fast enough to bit-bang the data from a floppy. One can load code into these boards and run fast enough to monitor the data stream of a floppy. I've hacked the ones used by Cardinal and DSI to use for some DSP projects. I've been considering doing the same to capture images of disk. I'd though it would be easiest to use the disk controller in the PC to deal with select, track stepping and head loads while using this board to read the data. Once the timing data is captured, one can store or decode at ones leisure. Dwight